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 Post subject: Used Raman Spectrometers
PostPosted: Thu Dec 28, 2017 6:40 pm 
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My boys will be selling used Raman Spectrometers. These units are mil spec, hand held, and can run analysis software either on an (Android) phone or a (Windows) laptop. Connection is via WiFi. Analysis software uses the RRUFF database. I believe they want $5k for them. There will be several with them at the Tucson show, so let them know if you are interested.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Dec 29, 2017 12:47 pm 
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Where at the Tucson show?


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Dec 29, 2017 2:51 pm 
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We don't have a booth. We can meet people at the dinner, or just let us know where you will be and we will find you.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Sat Dec 30, 2017 4:44 pm 
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I should mention that a Galaxy 6 (at least) should be used for the phone - it takes about 12 seconds then to identify the stone from the spectra (mostly loading the database). My much older phone (a Galaxy 4, I think) took 3-4 minutes to load the database. I suppose with a laptop with an SSD it would be much faster.
The software was designed to work with this spectrometer, but should work fine with most other spectrometers for gem identification.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Thu Jan 18, 2018 11:57 pm 
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Just got a stone with a spectra I didn't recognize.
Image

a little searching and it turns out to be

Image

This is from the http://www.ashadiamonds.com for their diamond simulant


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 1:03 am 
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So, they are using this spectrum to "prove" their simulant is diamond coated CZ?


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 1:38 pm 
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Yup - after a little bit of searching, I find it is partially diamond coated CZ (they use something else as well to help the diamonds stick as I understand it). If you look up diamond coated CZ Raman signatures, you will find a large number of spectra which don't look at all like this -- and this one from the company that makes them.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 1:47 pm 
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Curious. The diamond spectrum offered has nothing to indicate Type IIA....I guess they used their own knowledge of what they were testing.
Tempted to get a 4mm stone for $32 and see what kind of results I get.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 2:49 pm 
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yeah... that spectra wasn't in my database, so I wasn't sure what to do with it.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 3:44 pm 
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dchallener wrote:
yeah... that spectra wasn't in my database, so I wasn't sure what to do with it.

Why don't you simply measure its relative density and relative reflectivity?


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 4:44 pm 
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Hi Dr. Hanneman.
Normally sound advice.
BUT this stone is a fake-up.
CZ with a diamond coating....diamond coating is atoms in thickness usually.
Normally when these simulants are tested with sophisticated spectrographic instruments, the diamond doesn't show up at all.

David/Stephen: Can you post a pic of the stone? Have you tested it on pavilion facets? Does it exhibit an orange flash?


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 8:05 pm 
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I only tested it from the top. I will let Stephen or Tim take a picture - they are better at it. It is a fairly big stone and kind of peach in color.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 8:56 pm 
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Oh wow. this website is great....".... Therefore dirt, grime, hand oils, lotion, etc will stick less to the Asha because of the diamond coating, and your stone will remain much cleaner than an ordinary CZ."

Thats because diamonds dont like grease and oil...grease table sorting must work by magic I suppose.

Sorry for the thread hijack. 5k on a Raman seems pretty awesome really. Asha diamonds....not so much.

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 Post subject: Re: Used Raman Spectrometers
PostPosted: Fri Jan 19, 2018 10:07 pm 
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Check this article from GIA 2012 About diamond coated CZ.
Experiments with Raman did NOT detect the diamond coating:
Full article:
https://www.gia.edu/doc/Characterizatio ... antine.pdf
G&G, Spring 2012 wrote:
With the exception of Raman spectroscopy, standard
analytical methods and instruments used in major
gemological laboratories are unlikely to detect a very
thin, colorless, carbon-containing coating on a polished
CZ or other gem material—or, if such a coating is
detected, to confirm that the carbon is in the crystalline
form of diamond. Raman spectroscopy is the most
established method for determining the type of carbon
present in a material.

The diamond Raman peak
(produced by sp3bonding of carbon atoms)
is located at 1332 cm–1, while the graphite-related Raman feature
(where the carbon has sp2 bonding) is a broad band
centered at ~1550 cm–1
(see Zaitsev, 2001, pp. 69–70,111–112).
Our Raman spectroscopy investigation was
unable to detect the 1332 cm–1 or the ~1550 cm–1
peak even with a 325 nm UV laser at liquid-
nitrogen temperatures on the CZ plate represented as
having a “thick” coating.



For fun, Team Challener, can you super impose the spectrum for CZ on top of your spectrum for Diamond and Asha?
Thanks.


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 Post subject: Re: Used Raman Spectrometers
PostPosted: Sat Jan 20, 2018 5:57 am 
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Hi, perfectly matched cubic zirconia spectrum - http://www.ramansystems.com/english/gem ... alysis.htm
For cubic zirconia spectrum could be different due to doping, most probably formation around 1300 cm-1 is PL of rare earth element doping as the stabilizer. P


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